I am going insane

Are you saying that there is a big difference of the volume between a usb connection and a jack connection?

Of course lol. See, USB can normally deliver more power than what the 3.5mm jack can deliver because the USB standard dictates so. There’s no standard for on-board audio.
That also means that your old pair of headphones has an integrated DAC/amp that utilizes the USB power and signal.

Try this, plug in your old headset using only the 3.5mm jack. It’ll actually be a bit quieter than the X2HRs because it has a higher impedance.

So, you will need an amp after all

alright, let me try that little experiment of yours.
And now the question, what amp?

It all depends on your budget. I stick with my Liquid Spark recommendation, or the Syba Sonic if you want something for 1/3rd the price

Well the Liquid Spark isn’t available in my country

For a cheap option, you might look at something like one of the USB dongles. I have this one:

It’s not going to match the quality of something like the Liquid Spark, but it should give you the volume boost you need.

You don’t need expensive one, just get Fiio Q1 mk2 or btr3 if you want both portable uses with iem.

I’d just like to throw out the fx audio dac-x6 as a potential option. I have no experience or knowledge of how it performs, I just know that it is an dac/amp and fits your budget, no idea how it compares to similarly priced dac/amps.

FiiO E10K Pro or BTR3 should be enough. I think E10K would suit you better since you’re on a desktop, but you can also use btr3 with your phone.

How much is the e10k where you live?

The E10k is 82 euros

I ain’t buying from amazon, sorry, but the delivery fees are too high, it takes too long and I am not sure about the warranty

Is the Sennheiser GSX 1000 a way better option?
Cause I could save up for it and just use the headphones like this until then.

You don’t need to buy from Amazon, I was just suggesting something along those lines: whatever is available for cheap in your area.

What about FiiO BTR3?
I think you’d be surprised, I’ve heard amazon is pretty straight forward with returns. I don’t know how much shipping is to Romania, but from amazon uk I can get shipping for about 8€ to Estonia, so that’s like 69€ for the E10K including shipping. If you’re really doubt it you can buy 2 years accidental damage + 1 year breakdown insurance for it from amazon.
I think E10K is more future proof than GSX 1000, incase you want to upgrade your headphones to something that has more impedance in the future, tho what I said should be taken with a grain of salt since I’m not a expert and haven’t used neither one of them.

I can get the Fiio BTR3 for 60 euros here and I have everything I need, a good return policy, 2 year warranty, the lot.
But isn’t that dac designed for smartphones? I’m not an expert either, but I think the E10k might be significantly better cause it’s designed for pc use. Here, I can get it for 82 euros

And why are saying that the Fiio E10k is more future proof than the GSX 1000?
Do you mean that the GSX 1000 isn’t really powerful and only works with low impedance cans?

Yes, if you are going with something that’s really hard to drive, as I said not sure tho and I don’t want to talk out of my ass.

You might want to look into GSX 1000 on this forum or look up some comparisons on other forums, I haven’t found any on HiFiGuides. E10K is probably a better dac.
I have the BTR3, haven’t used it with a PC yet, but you can use it as a dac if needed, it’s a neat piece of kit.

Hmm, I honestly don’t think I’ll use pair of cans with more than 150 ohms, but, still, this is my first pair of audiophile headphones.
I don’t know, honestly.
But how good is the Fiio E10 k? Is is a really good dac for that price? Or a really good dac in general?

Can’t say, since I haven’t used one, but the general consensus seems to be it’s good for that price.
You could look up SMSL M3, which I own, it should be around the same price, but since you’re in Romania the pricing could be higher.